Since it's not obvious how to track down such errors, I'll try to give a step-by-step explanation below.

0. In order to even find such errors, you should be logged in on the Kindle, and watch "showlog -f". Debug mode may be a good decision as well, though it's not needed for this particular mistake.
1. The error is initially caused by "java.text.MessageFormat.format()" at "com.amazon.ebook.booklet.reader.plugin.notesandma rks.AnnotationView.updateAnnotations()".
2. This indicates a wrong translation somewhere, but how do we find out where?
3. We find out from the stack trace that we should probably take a look at the method updateAnnotations() in com.amazon.ebook.booklet.reader.plugin.notesandmar ks.AnnotationView.
4. http://wiki.mobileread.com/wiki/Kind...on.27s_classes gives some valuable hints on how to achieve this.
5. In the decompiled method, we only find one line of interest: String a = rb.getString("annotation.info.page");
6. ... where: rb = ResourceBundle.getBundle("com.amazon.ebook.booklet .reader.plugin.notesandmarks.resources.AnnotationR esources");
7. Finally, we take a look at that resource in transifex:

... and you should immediately see where the error comes from.

(This uses eureka's previous hint of enabling "verbose editing" on transifex to display resource names, shown in green). And it clearly shows that care must be taken while translating...